
.arrow{
  display: none;
}
.banner-container:hover .arrow{
  display: block;
}
.arrow span{
  position: absolute;
  color: #fff;
  width: 20px;
  height: 30px;
  line-height: 30px;
  top: 50%;
  transform: translateY(-50%);
  background: rgba(0,0,0,.5);
  box-sizing: border-box;
  cursor: pointer;

  
}
.arrow span:hover{
  background: rgba(0,0,0,.7);
}

.arrow .left{
  left: 0;
  border-radius: 0 30px 30px 0;
}

.arrow .right{
  right: 0;
  border-radius: 30px 0 0 30px;
  padding-left: 6px;
}